This is a meaningless comparision. Because dissimilar CPU architectures are compared, it in no way substantiates the claim that 8 cores are better than four. A meaningful comparison would have been the Z600 with one quad core CPU versus the same workstation with two quad core CPUs. My guess is that there would be vitually no difference in performance and certainly not enough to justify the 300% higher cost of a dual CPU Z600 and a single CPU Z400 running at the same clock speed.